A phase-contrast distance measuring technique is known as a distance measuring technique applicable to digital still cameras and video cameras.
PTL 1 discloses a solid-state imaging device in which some of pixels have a ranging function using a phase contrast method. The individual pixels have light receiving portions each including a microlens and a photoelectric conversion section. The light receiving portions have the characteristic of having sensitivity to a beam that is incident thereon at a small angle range through the microlens by guiding light incident at a specific angle to the photoelectric conversion sections. With this configuration, beams that have passed through partial regions on the pupil of the image-forming optical system are detected. Two images generated from the beams that have passed through different regions on the pupil of the camera lens are acquired by different light receiving portions. The distance between the two images is estimated, and the defocusing amount is calculated by triangulation using a stereo image to perform ranging.
This method does not need to move the lens to measure the range, in contrast to the conventional contrast method, thus allowing high-speed high-accuracy ranging.
The signals acquired by the light receiving portions of the pixels can be used as imaging signals for generating an image, thus allowing imaging and ranging at the same time.
PTL 2 discloses a focus detection apparatus equipped with an imaging device having a pair of pixel groups that receive beams that have passed through different pupil regions of an image-capturing optical system and output a first image signal and a second image signal, respectively.
The focus detection apparatus includes a calculation unit that subtracts a value obtained by multiplying a second image signal by a second factor from a value obtained by multiplying a first image signal by a first factor to generate a first correct image signal and that subtracts a value obtained by multiplying a first image signal by a fourth factor from a value obtained by multiplying a second image signal by a third factor to generate a second correct image signal; and a focus detection unit that determines the defocusing amount on the basis of the phase difference between the first and second correct image signals.